The pullup is one of the most effective exercises for building a v-shaped torso. Unfortunately, the move isn't easy. That's why you see only the fittest men cranking out rep after rep of the old-school exercise. "The pullup is a true test of upper-body strength and endurance," says Todd Durkin, C.S.C.S., author of The IMPACT! Body Plan. "It targets your lats, traps, core, and biceps all at once."

How do you stack up? Find out with this back-shredding, shoulder-sculpting, arm-pumping pullup challenge. Durkin completed 33 pullups. What was your score? Let us know in the comments below.